The research projects described in this program will investigate strategies aimed at enhancing the efficacy of Rev M10 and other genes in HIV infected individuals alone or in combination with the antiviral treatment or immunotherapy. However, two immunologic concerns surfaces which may limit the success of this therapeutic modality. First is the potential immunogenicity of Rev M10 and the vectors employed to facilitate transfection. Though not yet observed as administered in the current human gene transfer protocols immune responses elicited by gene transfer eliminate transfected cells, thereby limiting duration of transgene expression. Second, stable introduction of the transgene may produce toxic effects, such as aberrant cytokine production, altered T cell function, and transformation. The Immunology Core will address these issues in patients enrolled in the clinical trials of Projects 1 and 2 of this program. The Immunology Core will provide a variety of assays aimed at elucidating the human immune response to Rev M10 transduced hematopoietic cells. These assays include 1) Rev-driven proliferation, 2) Rev-specific cytotoxicity, 3) limiting dilution analysis (LDA) for Rev-specific IL-2 producing helper T lymphocytes (HTL), 4) LDA for cytotoxic T lymphocytes (CTL) responding to Rev M10 transduced cells, 5) ELISA for Rev-driven cytokine production, and 6) ELISA for Rev-specific serum antibodies. It should be noted that little is known regarding the human immune response to Rev M10 gene transfer, and the potential consequence of the immune response on the persistence of Rev M10 transduced cells. Hence, this comprehensive immunologic analysis represents the first attempt define deleterious responses associated with decreased efficacy of Rev M10 gene transfer. In addition, the Immunology Core will perform toxicity assays on PBL transduced with new generation Rev M10 encoding vectors developed in Projects 1, 3, and 4 of this program in preparation of FDA and RAC approval. Assays to be performed on transduced cells include: 1) spontaneous and mitogen driven cytokine production (ELISA), 2) spontaneous and mitogen driven proliferation, 3) the ability to respond to recall antigens (LDA of tetanus toxoid reactive cells), and 4) transformation potential following infection into SCID mice. Many of the assays described above require equipment and technologies which are currently in place in the Immunology Core Laboratory, but not in the labs of the individual project directors. Hence, the Immunology Core will streamline both monetary and time costs which would otherwise be required to duplicate and develop these assays.